Recently, the functions of portable apparatus such as a mobile telephone, portable information terminal and the like, have been improved dramatically. As a display device in the apparatus of this kind, for example, a display device using a liquid crystal display panel is employed. Such display device has been required to display more information. For this reason, the resolution of a display screen has been increased year by year, and an image has been required to display in color and high image quality. Accordingly, the electric power consumption in the display device tends to increase.
In general, these portable apparatuses are driven by batteries, and it is required to lengthen their operating time. Therefore, it is seriously required to reduce the electric power consumption as much as possible, including the display device.
In view of the aforementioned circumstances, a structure, which employs, what is called, a partial display system so as to reduce the electric power consumption in the display device is now used in increasing numbers. In the partial display system, a full-screen display is performed if necessary, however an icon etc. are displayed in only a part of the display screen without performing the full-screen display and the other parts are turned into a non-display state in a stand-by mode, for example.
As a driving system for performing the partial display, various systems are employed. In any system, a non-display area is set to a state in which nothing is displayed by applying no voltage on display pixels therein, and thus the non-display area is set in black or white. For example, in the case where a display or non-display area is set in the unit of scanning lines, the scanning lines belonging to the non-display area are turned into a non-selected state, so that the display pixels are set to be applied with no voltage. In this case, in the case where the display device is configured such that a white display is performed in the state where no voltage is applied on the display pixels (Normally white mode), the non-display area is displayed in white. On the other hand, in the case where the display device is configured such that a black display is performed in the state where no voltage is applied on the display pixels (Normally black mode), the non-display area is displayed in black.
As described above, the conventional non-display area in a partial display operation has been displayed only in white or black, which has been boring and uninteresting.